Subject: Re: [linux-audio-dev] Re: EVO-Linux Physical Modeling HD Sampler
From: Benno Senoner (sbenno_AT_gardena.net)
Date: Tue Jul 18 2000 - 01:23:31 EEST
On Mon, 17 Jul 2000, Juhana Sadeharju wrote:
>
> >>each envelope is an arbitrary succession straight lines
>
> We should write a separate library for envelopes because they are needed
> everywhere. Such library should be usable from graphical editor and from
> audio engine.
Such a ramp editor would be nice.
As soon we have the complete specs of the entire sample engine layout,
someone of you can start to work on this editor.
:-)
>
> Using many lines for approximating the often needed exponential envelopes
> could work, but it might be more efficient to do the same mathematically.
> Thus exponential envelopes (line in decibel scale) should be allowed.
The envelopes have to be very efficient and using math does not make sense
to me ( are you really thinking about calculating y=exp(x) at every iteration
??)
as said a few hundreds lines will aproximate the exponential curves VERY well,
and if you are not satisfied, you can always sample exp(x) sample per sample
:-)
the key point here is to keep the engine very efficient.
And today I added volume envelope support (with the method described on my
previous mail), and when playing 20 voices ( 6-7% of the PII400 CPU :-) ) ,
I did not notice a big performance difference when playing with or without
envelopes.
Benno.
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